SiCf/TC17复合材料界面剪切强度测试与有限元分析

界面强度对钛基复合材料的性能有重要影响。采用纤维顶出实验(push-outtest)对连续SiC纤维增强TC17复合材料的界面剪切强度进行了测试,采用SEM观察了样品的形貌。以纤维/基体完全分离后的摩擦力为出发点,采用有限元方法确定了复合材料成型过程中残余应力的产生温度,并计算了残余应力的分布,比较了顶出实验样品制备前后残余应力的变化情况及样品厚度、体积分数对残余应力分布的影响;采用内聚力模型(CZM)分析了界面的化学结合强度。结果表明:SiCf/TC17复合材料高温成型后的冷却过程中开始产生残余应力的温度为775℃;顶出实验样品制备后界面处生成了残余剪切应力,其大小和分布与样品的体积分数和厚度相关,界面处的残余剪切应力造成了界面剪切强度的测试结果与界面化学结合强度的差异;室温下SiCf/TC17复合材料的界面化学结合强度约为450MPa。

Interface shear strength test and finite element analysis of SiCf/TC17 composites

The property of continuous SiC fiber reinforced titanium matrix composites is strongly affected by the interface strength.The interface shear strength of SiC_f/TC17 was tested by fiber push-out test and then the microstructure of the sample was observed by SEM. The process of cooling from the composite consolidation temperature, specimen preparation for the push-out test, and the actual testing were simulated by using the finite element method. The initial temperature when residual stress begun to exist was identified through regarding the friction force when the fiber was completely separated from the matrix as the starting point.And the distribution of residual stress was analyzed before and after the sample preparation.The influence of the sample thickness and the fiber fraction volume on the distribution of the residual stress was studied.Cohesive zone model was used to analyze the interface chemical bonding strength.The results indicate that the initial temperature below which the residual stress starts to be generated is about 775 ℃.The residual shear stress is introduced at the interface after sample preparation.The difference between the test results of the interface shear strength and the interface chemical bonding strength is due to the existence of the interface residual shear stress.And the interface chemical bonding strength of SiC_f/TC17 composites is about 450 MPa at room temperature.